[feat] gateway pool

1 files changed, 229 insertions, 0 deletions

diff --git a/pkg/vpn/bonafide/gateways.go b/pkg/vpn/bonafide/gateways.go
new file mode 100644
index 0000000..6084985
--- /dev/null
+++ b/pkg/vpn/bonafide/gateways.go
@@ -0,0 +1,229 @@
+package bonafide
+
+import (
+	"errors"
+	"log"
+	"math/rand"
+	"sort"
+	"strconv"
+	"time"
+)
+
+const (
+	maxGateways = 3
+)
+
+// A Gateway is a representation of gateways that is independent of the api version.
+// If a given physical location offers different transports, they will appear as separate gateways.
+type Gateway struct {
+	Host      string
+	IPAddress string
+	Location  string
+	Ports     []string
+	Protocols []string
+	Options   map[string]string
+	Transport string
+	Label     string
+}
+
+/* TODO add a String method with a human representation: Label (cc) */
+/* For that, we should pass the locations to genLabels, and generate a string repr */
+
+type gatewayDistance struct {
+	gateway  Gateway
+	distance int
+}
+
+type gatewayPool struct {
+	available []Gateway
+	/* ranked is, for now, just an array of hostnames (fetched from the
+	geoip service). it should be a map in the future, to keep track of
+	quantitative metrics */
+	ranked     []string
+	userChoice string
+	locations  map[string]location
+}
+
+/* genLabels generates unique, human-readable labels for a gateway. It gives a serial
+   number to each gateway in the same location (paris-1, paris-2,...). The
+   current implementation will give a different label to each transport.
+*/
+func (p *gatewayPool) genLabels() {
+	acc := make(map[string]int)
+	for i, gw := range p.available {
+		if _, count := acc[gw.Location]; !count {
+			acc[gw.Location] = 1
+		} else {
+			acc[gw.Location] += 1
+		}
+		gw.Label = gw.Location + "-" + strconv.Itoa(acc[gw.Location])
+		p.available[i] = gw
+	}
+	/* skip suffix if only one occurence */
+	for i, gw := range p.available {
+		if acc[gw.Location] == 1 {
+			gw.Label = gw.Location
+			p.available[i] = gw
+		}
+	}
+}
+
+func (p *gatewayPool) getLabels() []string {
+	labels := make([]string, 0)
+	for _, gw := range p.available {
+		labels = append(labels, gw.Label)
+	}
+	/* TODO return error if called when no labels have been generated */
+	return labels
+}
+
+func (p *gatewayPool) isValidLabel(label string) bool {
+	labels := p.getLabels()
+	valid := stringInSlice(label, labels)
+	return valid
+}
+
+func (p *gatewayPool) getGatewayByLabel(label string) (Gateway, error) {
+	for _, gw := range p.available {
+		if gw.Label == label {
+			return gw, nil
+		}
+	}
+	return Gateway{}, errors.New("bonafide: not a valid label")
+}
+
+func (p *gatewayPool) getGatewayByIP(ip string) (Gateway, error) {
+	for _, gw := range p.available {
+		if gw.IPAddress == ip {
+			return gw, nil
+		}
+	}
+	return Gateway{}, errors.New("bonafide: not a valid ip address")
+}
+
+func (p *gatewayPool) setAutomaticChoice() {
+	p.userChoice = ""
+}
+
+func (p *gatewayPool) setUserChoice(label string) error {
+	if !p.isValidLabel(label) {
+		return errors.New("bonafide: not a valid label for gateway choice")
+	}
+	p.userChoice = label
+	return nil
+}
+
+func (p *gatewayPool) setRanking(hostnames []string) {
+	hosts := make([]string, 0)
+	for _, gw := range p.available {
+		hosts = append(hosts, gw.Host)
+	}
+
+	for _, host := range hostnames {
+		if !stringInSlice(host, hosts) {
+			log.Println("ERROR: invalid host in ranked hostnames", host)
+			return
+		}
+	}
+
+	p.ranked = hostnames
+}
+
+func (p *gatewayPool) getBest(transport string, tz, max int) ([]Gateway, error) {
+	gws := make([]Gateway, 0)
+	if len(p.userChoice) != 0 {
+		gw, err := p.getGatewayByLabel(p.userChoice)
+		gws = append(gws, gw)
+		return gws, err
+	} else if len(p.ranked) != 0 {
+		return p.getGatewaysByServiceRank(transport, max)
+	} else {
+		return p.getGatewaysByTimezone(transport, tz, max)
+	}
+}
+
+func (p *gatewayPool) getGatewaysByServiceRank(transport string, max int) ([]Gateway, error) {
+	gws := make([]Gateway, 0)
+	for _, host := range p.ranked {
+		for _, gw := range p.available {
+			if gw.Transport != transport {
+				continue
+			}
+			if gw.Host == host {
+				gws = append(gws, gw)
+			}
+			if len(gws) == max {
+				goto end
+			}
+		}
+	}
+end:
+	return gws, nil
+}
+
+func (p *gatewayPool) getGatewaysByTimezone(transport string, tzOffsetHours, max int) ([]Gateway, error) {
+	gws := make([]Gateway, 0)
+	gwVector := []gatewayDistance{}
+
+	for _, gw := range p.available {
+		if gw.Transport != transport {
+			continue
+		}
+		distance := 13
+		gwOffset, err := strconv.Atoi(p.locations[gw.Location].Timezone)
+		if err != nil {
+			log.Printf("Error sorting gateways: %v", err)
+			return gws, err
+		} else {
+			distance = tzDistance(tzOffsetHours, gwOffset)
+		}
+		gwVector = append(gwVector, gatewayDistance{gw, distance})
+	}
+	rand.Seed(time.Now().UnixNano())
+	cmp := func(i, j int) bool {
+		if gwVector[i].distance == gwVector[j].distance {
+			return rand.Intn(2) == 1
+		}
+		return gwVector[i].distance < gwVector[j].distance
+	}
+	sort.Slice(gwVector, cmp)
+
+	for _, gw := range gwVector {
+		gws = append(gws, gw.gateway)
+		if len(gws) == max {
+			break
+		}
+	}
+	return gws, nil
+}
+
+func newGatewayPool(eip *eipService) *gatewayPool {
+	p := gatewayPool{}
+	p.available = eip.getGateways()
+	p.locations = eip.Locations
+	p.genLabels()
+	return &p
+}
+
+func tzDistance(offset1, offset2 int) int {
+	abs := func(x int) int {
+		if x < 0 {
+			return -x
+		}
+		return x
+	}
+	distance := abs(offset1 - offset2)
+	if distance > 12 {
+		distance = 24 - distance
+	}
+	return distance
+}
+
+func stringInSlice(a string, list []string) bool {
+	for _, b := range list {
+		if b == a {
+			return true
+		}
+	}
+	return false
+}